John Key is hanging on in last place on the National Business Review Rich List.

Key is valued at $50m, the same as last year after his estimated fortune fell from $55m in 2011 to $50m in 2012.

Key first made the Rich List in 2008 with an estimated wealth of $50m. The Prime Minister had rejected the accuracy of the list in past years.

Key, who made his money as a currency trader owns several properties around New Zealand and around the world.

Because of his political position, Key's money is invested for him in a blind trust, meaning he doesn't actually know where it is held so cannot be accused of political interference to line his own pocket.

Elsewhere, the list showed the rich are getting richer with the total minimum net worth of those on the list was up $3.5 billion on last year to $47.8b.

Auckland business tycoon Graeme Hart was back at No 1 after being usurped by Russian steel magnate Alexander Abramov last year.

The packaging tycoon's wealth is estimated to be $6.4b, an increase of $400 million from last year.

Waikato-born investment banker Richard Chandler was second on the list with $3.7b, $1.3b less than last year.

The Todd family ($2.9b) and Chandler's brother, Christopher ($1.3b), maintained their wealth to be third and fifth respectively.

Philanthropist Sir Owen Glenn - in the spotlight recently over his family violence inquiry - remained in eighth place with his $900m fortune.

Last year's list saw the addition of international investors in a bid to reflect the globalisation of wealth, with most investing enough to earn residency rights. This year's list had reverted to New Zealand's well-off, with the ranks of billionaires slipping to six from nine last year.

If the small group of New Zealand-based international billionaires was taken into account, the total wealth of members would total a record $60.4b.

The NBR uses valuations of listed shares, sales of private companies and other valuation techniques to estimate the wealth of those ranked.

It said the surge in wealth was through gains in most investment classes. The New Zealand equity market returned 25.9 per cent last year and had added 10 per cent in the first half of this year. The hot property market had also added to the stream of wealth.

New wealth had also been created through entrepreneurism, hard work and determination, the NBR said.

Hong Kong-born brothers John and Michael Chow closed out the list at $50m. The Naenae College-educated brothers have had ventures in property and the sex industry, developing the controversial high-rise Penthouse Clubs.

Four of this year's newcomers - Edwards, Ransom, Malcolm McDonald and Derek Jones - made their fortunes in the technology sector by developing software for an increasingly tech-savvy population.

Other profitable sectors included dairy farming, oil and gas exploration, insurance and food retailing, while construction made a comeback.

The sharemarket contributed to some big jumps in the wealth of existing NBR Rich Listers. This year's biggest success story was Xero, the online accounting software company co-founded by Edwards and Rod Drury.

Drury, who still owns more than 18 per cent of the company, saw his personal wealth skyrocket from $120m to $400m.

Former NBR Rich Listers returning this year are Craig Heatley, Earl and Lani Hagaman, Alan Pye and Humphry Rolleston.TOP TEN: